1. Field of the Invention
The invention is concerned with control systems for the hydrostatic drive of a vehicle. More particularly the invention is concerned with an improved mechanical arrangement for controlling the speed and steering functions of the control system of a hydrostatically driven vehicle. Typically such a vehicle will be driven by ground engaging means as for example by an endless track or by tires. Full control of both speed and steering is provided by the mechanical arrangement of the present invention.
2. Prior Art
The prior art has been primarily concerned with hydraulically controlling speed and steering functions of a hydrostatic control system. Such systems are more costly to manufacture than an all mechanical arrangement. Further, good steering modulation through the use of hydraulic cylinders is harder to obtain than with a mechanical arrangement. Really satisfactory steering modulation has never been fully attained with the use of hyraulic cylinders. Still further a hydraulic system is somewhat less reliable than a purely mechanical arrangement, requires the use of more space, and is generally more costly to repair.
Accordingly the present invention is concerned with providing a unique and positive acting mechanical arrangement for controlling the speed and steering functions to be infinitely variable within selected limits in a control system for a hydrostatic drive of a vehicle. The arrangement of the present invention provides positive and infinitely variable steering and in fact provides a capability for spot turning as by having a different direction of rotation for the ground engaging means on each side of a vehicle.